From Michael Eisen's blog:

Yuval Levin, former Executive Director of the President's Council on Bioethics, has an op-ed in Tuesday's Washington Post arguing that Obama's new stem cell policy is dangerous. Levin does not argue that stem cell research is bad. Rather he is upset that Obama did not dictate which uses of stem cells are appropriate, but rather asked the National Institutes of Health to draft a policy on which uses of stem cells are appropriate:

It [Obama's policy] argues not for an ethical judgment regarding the moral worth of human embryos but, rather, that no ethical judgment is called for: that it is all a matter of science.

This is a dangerous misunderstanding. Science policy questions do often require a grasp of complex details, which scientists can help to clarify. But at their core they are questions of priorities and worldviews, just like other difficult policy judgments.

Lost in this superficially unobjectionable - if banal - assertion of the complexity of ethical issues involving science is Levin's (and many other bioethicists) credo: that the moral complexity of scientific issues means that scientists should not make decisions about them.